Spatially relaying radiation components

Abstract

A method of spatially relaying a first radiation component (1) having a first wavelength and a second radiation component (2) having a second wavelength different from the first radiation component (1), using an optical relaying device (10) which comprises a transparent plate (11) having anti-reflection coatings (12, 13) on both side surfaces thereof, comprises transmitting the first radiation component (1) across the optical relaying device (10) with predetermined incident (a) and emergent angles (β), resp., wherein said anti-reflection coatings (12, 13) being effective for the first radiation component (1) at the incident and emergent angles (α, β), resp., and reflecting the second radiation component (2) at the optical relaying device (10) with a predetermined reflection angle (a) being equal to at least one of said incident and emergent angles (α, β), wherein the first and second radiation components (1, 2) are split from each other toward different directions or combined into a common beam path. Furthermore, an optical relaying device (10) and a resonator device, in particular enhancement cavity device (100) and a laser resonator, are described.

Description

FIELD OF THE INVENTION[0001]The present invention relates to a method of spatially relaying, in particular splitting or combining, radiation components with different wavelengths, like spatially relaying a first radiation component, which e.g. includes a fundamental wavelength in an optical wavelength range, and a second radiation component, which e.g. includes shorter wavelengths compared with the fundamental wavelength, in particular second or higher harmonic wavelengths relative to the fundamental wavelength. Furthermore, the present invention relates to a method of output coupling radiation from an optical resonator like e.g. an enhancement cavity or a laser resonator, to a method of conducting a pump-probe measurement, to an optical relaying device being capable of wavelength-selective relaying, in particular splitting or combining of radiation components, and to a resonator device, in particular an enhancement cavity or a laser resonator provided with the optical relaying devi...

AI Technical Summary

Benefits of technology

The invention provides an improvement to the conventional Brewster plate concept for extracting high harmonics of a fundamental field in an enhancement cavity. By using anti-reflection coatings, the Brewster angle can be avoided, resulting in a more efficient output coupler for XUV. The optical relaying device can be positioned at an angle above the Brewster angle to increase the reflection of the second radiation component and reduce losses. The device has low surface quality requirements and produces a high-quality beam containing all new spectral components. The invention also provides a method for out-coupling harmonic radiation from an enhancement cavity using the optical relaying device.

Problems solved by technology

However, when XUV radiation is produced inside the cavity, its output coupling immediately becomes a challenging task.

One of the main limitations of the Brewster plate is a low XUV out-coupling efficiency (criterion a).

Further, the Brewster plate is a compromise between XUV reflectivity and acceptable optical, thermal and nonlinear properties of the Brewster plate material as it is difficult to find a material fulfilling criteria (a) and (f).

However, the XUV output coupling efficiency is only comparable to the Brewster plate method achieving e.g. 10% for the 70 nm wavelength (see D. C. Yost et al. in “Opt. Lett.” vol.

Furthermore, the maximum intra-cavity power level is limited to e.g. 5 kW and caused by the damage of a dielectric coating (see A. Cingöz, cited above).

Thus, this method doesn't meet the above criteria (a), (b) and (f).

However, the aperture clips the harmonics of lower orders thus decreasing the XUV bandwidth of out-coupled high harmonics from the long-wavelength side.

Furthermore, the hole introduces also losses to the driving light field and decreases the enhancement factor of the cavity.

The process may result in conversion efficiencies much lower than that of a “standard” HHG with a single fundamental beam.

Moreover, the output coupling efficiency of this method is limited by the cavity design.

Moreover, the two frequency components need not be correlated by a nonlinear process, but can stem from uncorrelated radiation sources.

As a main disadvantage, this conventional technique was restricted to relatively low harmonics (up to 21th harmonic).

For higher harmonics, i.e. for lower wavelengths, which occur in particular in enhancement cavities, the efficiency of the conventional reflecting plate is too low.

Furthermore, the conventional reflecting plate could not be used in an enhancement cavity as the IR radiation component is split by the plate to different directions.

This would result in an unacceptable lost in circulating IR intensity.

The diffraction grating has an essential disadvantage in terms of spatially dispersing EUV components.

However, these techniques cannot be applied if the short wavelength component has a wavelength in a range of e.g. XUV radiation, as the wavelength separation is done within the plate volume, where the XUV radiation would be lost due to absorption.

However, the application of dichroic mirrors is restricted if one of the beams has a wavelength in the XUV range as this beam would be absorbed by the dichroic mirror.

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